VFIO: unregister IOMMU notifier on error recovery path

On error recovery path in function vfio_create_group(), it should
unregister the IOMMU notifier for the new VFIO group. Otherwise it may
cause invalid memory access later when handling bus notifications.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

1 files changed, 15 insertions, 16 deletions

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 56097c6d072d..3b7fa7967221 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -191,6 +191,17 @@ static void vfio_container_put(struct vfio_container *container)
         kref_put(&container->kref, vfio_container_release);
 }
 
+static void vfio_group_unlock_and_free(struct vfio_group *group)
+{
+        mutex_unlock(&vfio.group_lock);
+        /*
+         * Unregister outside of lock.  A spurious callback is harmless now
+         * that the group is no longer in vfio.group_list.
+         */
+        iommu_group_unregister_notifier(group->iommu_group, &group->nb);
+        kfree(group);
+}
+
 /**
  * Group objects - create, release, get, put, search
  */
@@ -229,8 +240,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
 
         minor = vfio_alloc_group_minor(group);
         if (minor < 0) {
-                mutex_unlock(&vfio.group_lock);
-                kfree(group);
+                vfio_group_unlock_and_free(group);
                 return ERR_PTR(minor);
         }
 
@@ -239,8 +249,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
                 if (tmp->iommu_group == iommu_group) {
                         vfio_group_get(tmp);
                         vfio_free_group_minor(minor);
-                        mutex_unlock(&vfio.group_lock);
-                        kfree(group);
+                        vfio_group_unlock_and_free(group);
                         return tmp;
                 }
         }
@@ -249,8 +258,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
                             group, "%d", iommu_group_id(iommu_group));
         if (IS_ERR(dev)) {
                 vfio_free_group_minor(minor);
-                mutex_unlock(&vfio.group_lock);
-                kfree(group);
+                vfio_group_unlock_and_free(group);
                 return (struct vfio_group *)dev; /* ERR_PTR */
         }
 
@@ -274,16 +282,7 @@ static void vfio_group_release(struct kref *kref)
         device_destroy(vfio.class, MKDEV(MAJOR(vfio.devt), group->minor));
         list_del(&group->vfio_next);
         vfio_free_group_minor(group->minor);
-
-        mutex_unlock(&vfio.group_lock);
-
-        /*
-         * Unregister outside of lock.  A spurious callback is harmless now
-         * that the group is no longer in vfio.group_list.
-         */
-        iommu_group_unregister_notifier(group->iommu_group, &group->nb);
-
-        kfree(group);
+        vfio_group_unlock_and_free(group);
 }
 
 static void vfio_group_put(struct vfio_group *group)